Vanadium compensated, SI SiC single crystals of NU and PI type and the crystal growth process thereof

Patent metadata

Field	Value
Publication number	US-RE48378-E
Application number	US-201715583538-A
Country	US
Kind code	E1
Filing date	May 1, 2017
Priority date	May 24, 2012
Publication date	Jan 5, 2021
Grant date	Jan 5, 2021

Abstract

In a crystal growth apparatus and method, polycrystalline source material and a seed crystal are introduced into a growth ambient comprised of a growth crucible disposed inside of a furnace chamber. In the presence of a first sublimation growth pressure, a single crystal is sublimation grown on the seed crystal via precipitation of sublimated source material on the seed crystal in the presence of a flow of a first gas that includes a reactive component that reacts with and removes donor and/or acceptor background impurities from the growth ambient during said sublimation growth. Then, in the presence of a second sublimation growth pressure, the single crystal is sublimation grown on the seed crystal via precipitation of sublimated source material on the seed crystal in the presence of a flow of a second gas that includes dopant vapors, but which does not include the reactive component.

First claim

The invention claimed is:

1. A crystal growth method comprising:
(a) providing a SiC single crystal seed and a polycrystalline SiC source material in spaced relation inside of a growth crucible that is disposed inside of a furnace chamber, the growth crucible disposed inside of a furnace chamber defining a growth ambient; and
(b) sublimation growing a SiC single crystal on the SiC seed crystal via precipitation of sublimated SiC source material on the SiC seed crystal; and
(c) causing a reactive atmosphere to form in the growth ambient that reacts with background nitrogen and boron present in the growth ambient forming a solid nitride compound with the background nitrogen and a gaseous boron halide compound with the background boron.

2. The method of claim 1 , wherein the reactive atmosphere includes a halide vapor compound and one or more gases.

3. The method of claim 2 , wherein:
the halide vapor compound is comprised of (1) fluorine or chlorine, and (2) tantalum or niobium; and
the one or more gases includes argon, hydrogen, or a mixture of argon+hydrogen.

4. The method of claim 2 , further including:
(d) following step (c), changing the atmosphere in the growth ambient to a non-reactive atmosphere; and
(e) following step (d), introducing into the growth ambient a vanadium dopant that causes the portion of the SiC single crystal sublimation growing on the SiC seed crystal after step (d) to be fully compensated and semi-insulating doped with vanadium.

5. The method of claim 4 , wherein step (e) further includes introducing into the growth ambient a dopant of boron or nitrogen.

6. The method of claim 4 , wherein, in step (e), the vanadium dopant is introduced into the growth ambient via controlled effusion.

7. The method of claim 4 , wherein introducing the vanadium dopant into the growth ambient in step (e) includes moving the vanadium dopant from a position outside the growth crucible where the vanadium dopant is a solid to a position inside the growth crucible where the vanadium dopant produces vanadium vapors during sublimation growth of the SiC single crystal.

8. The method of claim 4 , wherein a pressure inside of the growth crucible during sublimation growth of the SiC single crystal is between 1 and 100 Torr.

9. A crystal growth method comprising:
(a) introducing a polycrystalline source material and a seed crystal into a growth ambient comprised of a growth crucible disposed inside of a furnace chamber;
(b) in the presence of a first sublimation growth pressure in the growth ambient, sublimation growing a single crystal on the seed crystal via precipitation of sublimated source material on the seed crystal in the presence of a flow of a first gas that includes a reactive component that reacts with gaseous nitrogen in the growth ambient forming a solid nitride compound, reacts with boron in the growth ambient forming a gaseous boron halide compound, or both; and
(c) following step (b) and in the presence of a second sublimation growth pressure in the growth ambient, sublimation growing the single crystal on the seed crystal via precipitation of sublimated source material on the seed crystal in the presence of a flow of a second gas that includes dopant vapors, but which does not include the reactive component.

10. The method of claim 9 , wherein:
each sublimation growth pressure is between 1 and 100 Torr; and
the first and second sublimation growth pressures can be the same or different.

11. The method of claim 9 , further including introducing a source of the dopant vapors into the growth crucible between steps (b) and (c).

12. The method of claim 9 , wherein steps (b) and (c) are performed without exposing the growth ambient to room ambient atmosphere between said steps.

13. The method of claim 9 , wherein:
the reactive component of the first gas is a gaseous metal halide;
the dopant vapors of the second gas comprise gaseous vanadium; and
the second gas further comprises hydrogen, nitrogen or hydrogen+nitrogen.

14. A SiC crystal growth method comprising:
(a) providing a SiC single crystal seed and a polycrystalline SiC source material in spaced relation inside of a growth crucible that is disposed in a furnace chamber, wherein the crucible disposed in the furnace chamber defines a growth ambient; (b) initiating sublimation growth of a SiC single crystal on the SiC single crystal seed in the growth ambient; (c) following step (b), substantially removing background impurities of nitrogen and boron from the growth ambient during sublimation growth of the SiC single crystal on the SiC single crystal seed in the growth ambient; and (d) following step (c), introducing vanadium and boron dopants into the growth ambient during sublimation growth of the SiC single crystal on the SiC single crystal seed in the growth ambient thereby sublimation growing a PI-type SiC single crystal on the SiC seed crystal, wherein the grown PI-type SiC single crystal is semi-insulating, has a room-temperature resistivity of at least 10 10 Ohm-cm, and an activation energy of resistivity in the range between approximately 0.9 and 1.5 eV in the temperature range between room temperature and 400° C.

15. The SiC crystal growth method of claim 14 A SiC crystal growth method comprising:
(a) providing a SiC single crystal seed and a polycrystalline SiC source material in spaced relation inside of a growth crucible that is disposed in a furnace chamber, wherein the crucible disposed in the furnace chamber defines a growth ambient;
(b) initiating sublimation growth of a SiC single crystal on the SiC single crystal seed in the growth ambient;
(c) following step (b), substantially removing background impurities of nitrogen and boron from the growth ambient during sublimation growth of the SiC single crystal on the SiC single crystal seed in the growth ambient; and
(d) following step (c), introducing vanadium and boron dopants into the growth ambient during sublimation growth of the SiC single crystal on the SiC single crystal seed in the growth ambient thereby sublimation growing a PI-type SiC single crystal on the SiC seed crystal, wherein the PI-type SiC single crystal further comprises:
shallow acceptors present in larger concentrations than shallow donors; and
vanadium present in concentrations sufficient to achieve full compensation.

16. The SiC crystal growth method of claim 14 A SiC crystal growth method comprising:
(a) providing a SiC single crystal seed and a polycrystalline SiC source material in spaced relation inside of a growth crucible that is disposed in a furnace chamber, wherein the crucible disposed in the furnace chamber defines a growth ambient;
(b) initiating sublimation growth of a SiC single crystal on the SiC single crystal seed in the growth ambient;
(c) following step (b), substantially removing background impurities of nitrogen and boron from the growth ambient during sublimation growth of the SiC single crystal on the SiC single crystal seed in the growth ambient; and
(d) following step (c), introducing vanadium and boron dopants into the growth ambient during sublimation growth of the SiC single crystal on the SiC single crystal seed in the growth ambient thereby sublimation growing a PI-type SiC single crystal on the SiC seed crystal, wherein the PI-type SiC single crystal further comprises:
background nitrogen intentionally reduced in a concentration between 4·10 15 and 7·10 15 atoms-cm −3 ; and
intentionally introduced boron and vanadium dopants in concentrations between 9·10 15 and 2·10 16 atoms-cm −3 , and 9·10 16 and 2·10 17 atoms-cm −3 , respec

Assignees

• Ii Vi Delaware Inc

Inventors

• Zwieback Ilya
• Wu Ping
• Rengarajan Varatharajan
• Gupta Avinash K
• Anderson Thomas E
• Ruland Gary E
• Souzis Andrew E
• Xu Xueping

Classifications

• H01B3/025

  Other inorganic material · CPC title

• C30B23/002 Primary

  Controlling or regulating · CPC title

• C30B29/36

  Carbides · CPC title